There are two subspecies of Burrowing Owls in North America (Dechant et al.
2003, Johnsgard 1988). The breeding range of Athene cunicularia hypugaea
extends south from southern Canada into the western half of the United States
and down into Baja California, Mexico, and central Mexico. A. cunicularia
floridana occurs in Florida and adjacent islands. The winter range is similar
to the breeding range except that most owls from the northern areas of the Great
Plains and Great Basin migrate south (Haug et al. 1993).

MANAGEMENT STATUS:

California Species of Special Concern. Protected under the Migratory Bird Treaty
Act and as a "bird of prey" under the Raptor Recovery Act. Included
in the National Audubon Society's first Blue List of bird species undergoing
non-cyclic population declines and extreme habitat loss. In Arizona it is a
species of special concern and is considered a BLM Sensitive Species.

DISTRIBUTION:

HISTORICAL BREEDING DISTRIBUTION:

Burrowing Owls were once a common, locally abundant species throughout much
of California and Arizona. By the 1940s', Burrowing Owls had become scarce in
many portions of the desert southwest as a result of shooting and elimination
of ground squirrel burrows (Grinnell and Miller 1944). During the last 10-15
years, Burrowing Owls have been extirpated from approximately 8% of their former
range (J. Barclay, pers. comm. in Klute et al. 2003) including Sonoma, Marin,
Santa Cruz, and Napa counties.

CURRENT BREEDING DISTRIBUTION:

Burrowing Owls are widely distributed in proper habitat throughout the lowlands
of the state, but rare along the coast north of Marin County and extremely rare
east of the Sierra Nevada crest (Small 1994). Burrowing Owls are fairly common
residents along the Lower Colorado River Valley (Rosenberg et al. 1991) and
around the agricultural areas of the Imperial Valley. They are rare in the undisturbed
desert areas of the eastern and southeastern portion of California (Small 1994).
Breeding in Central California has been reduced to only three isolated populations:
the Central Valley, southern San Francisco Bay between Alameda and Redwood City,
and near the Livermore area (DeSante et al. 1997).

ECOLOGY:

AVERAGE TERRITORY SIZE

Nesting territory size was 4.8-6.4 ha in Minnesota (n = 2) and 4-6 ha in North
Dakota (n = 5-9 pairs) (Grant 1965). Foraging areas are considerably larger
than nesting areas. In s. Sackatchewan, mean foraging territory size for males
ranged from 14 to 481 ha (Haug 1985, Haug and Oliphant 1990). Home range and
foraging area may overlap between different pairs, with only the burrow being
actively defended (Coulombe 1971, Johnsgard 1988).

FOOD HABITS

FORAGING STRATEGY:

Burrowing Owls hunt by walking, running, hopping along the ground, flying from
a perch, hovering, particularly over tall vegetation, and fly-catching in mid
air. Prey is caught with the feet then transferred to the beak for carrying
and is presented to the female or chicks. Burrowing owls are known to cache
food in their burrows. They hunt throughout the 24-hour day, but are mainly
crepuscular, hunting at dusk and dawn. Burrowing Owls tend to hunt insects in
daylight and small mammals at night. Their keen binocular vision is very useful
because they hunt mostly in the early evening and into the night (Corman and
Wise-Gervais 2005). When hunting from a position on a fencepost, they use a
bobbing motion which amplifies the effect of their binocular vision and provides
depth perception.

Individual Burrowing Owls have moderate to high site fidelity to general breeding
areas, prairie dog colonies, and even to particular nest burrows (Klute et al.
2003). Burrow and nest sites are reused at a higher rate if the bird has reproduced
successfully during the previous year. In non-migratory populations, they use
and maintain burrows year-round (Haug et al. 1993).

NEST SITE:

Favored nest burrow sites are those in relatively sandy sites (possibly for
ease of modification and drainage), areas with low vegetation around the burrows
(to facilitate the owl's view and hunting success), holes at the bottom of vertical
cuts with a slight downward slope from the entrance, and slightly elevated locations
to avoid flooding. In addition to burrows, the owls also require perching locations
and frequently use fence posts or the top of mounds outside the burrow.

NEST CONCEALMENT

Before the start of egg laying, adults will often adorn their burrows with
various types of ornaments believed to help disguise the owls' scent such as
animal dung, shredded paper, cigarettes butts, and pieces of torn cloth.

NEST TYPE:

The nest burrow is a long underground burrow lined with grass and roots (Corman
and Wise-Gervais 2005). Burrowing Owls typically use burrows created by other
animals such as prairie dogs, kangaroo rats, ground squirrels, especially the
California ground squirrel (Collins 1979), kit foxes, and desert tortoises.

Grant (1965) observed a display flight characterized by rapid ascent of approximately
30 m, hovering for 5-10 seconds, rapid descent of 15 m and repeat of this sequence.
Thomsen (1971) observed circular flights of approximately 40 m in diameter performed
mainly by males. Other displays observed near the nest burrow include mutual
billing and preening of head and facial areas, presentation of food to female,
male singing Primary Song (Haug et al. 1993).

The female incubates the eggs and the male is responsible for providing her
with food during this period.

INCUBATION PERIOD:

21 to 28 days (Ehrlich et al. 1988).

DEVELOPMENT AT HATCHING:

Altricial.

NESTLING PERIOD:

The owlets open their eyes and begin to show evasive behavior at 5 days (Baicich
and Harrison 1997). At approximately two weeks of age, chicks will huddle around
the entrance of the burrow to await food (Johnsgard 1988). Chicks are able to
take short flights at 4 weeks of age, and can fly well by 6 weeks of age. Fledging
occurs at 44 days (Landry 1979).

PARENTAL CARE:

Male does all the hunting while young require brooding. Female begins hunting
as young become less dependent (Haug et al. 1993). Burrowing Owls often relocate
chicks to "satellite" burrows to presumably reduce the risk of predation
(Desmond and Savidge 1998) and possibly to avoid nest parasites (Dechant et
al. 1999).

POST FLEDGING BIOLOGY OF OFFSPRING:

Dispersing young use satellite burrows in the vicinity of their natal burrows
for about two months after hatching before departing the natal area (King and
Belthoff 2001).

NUMBER OF BROODS:

Burrowing Owls typically raise one brood per year, but replacement clutches
are often laid if the first attempt is lost (Corman and Wise-Gervais 2005).

BROOD PARASITISM:

Never observed (Haug et al. 1993).

LANDSCAPE FACTORS

ELEVATION:

Burrowing Owl nests have been found from 200 feet below sea level at Death
Valley up to 12,000 feet at the Dana Plateau in Yosemite (CDFG 2000).

Loss of Burrowing Owls on private lands within urban areas is expected under
current land-use regulations (Klute et al. 2003). Because of the large numbers
of Burrowing Owls that reside within the agricultural matrix of the Central
and Imperial valleys, change in methods of farming practices, particularly water
conveyance, is likely to impact Burrowing Owl numbers (Rosenberg and Haley In
press).

PESTICIDE USE:

A significant negative impact on survival and reproductive success, believed
to be due to direct toxicity, was observed when Carbofuran, a carbamate insecticide,
was sprayed over nest burrows (James and Fox 1987). Burrowing Owls have been
incidentally poisoned and their burrows destroyed during eradication programs
aimed at rodent colonies (Zarn 1974, Remsen 1978, Collins 1979). Indirect mortality
due to contaminated prey may be significant, but this is unknown to date (Haug
et al. 1993). Municipal governments and agricultural representatives should
be encouraged to reduce or restrict the use of pesticides and to use pesticides
of low toxicity to nontarget species (Thomson 1988).

Data for Western Burrowing Owls in most of the U.S. are insufficient to estimate
trends in abundance. Limited data suggest that they are decreasing in some areas,
but may be stable or increasing in others (Klute et al. 2003). Surveys in California
in 1986-91 found population decreases of 23-52% in the number of breeding groups
and 12-27% in the number of breeding pairs of owls (DeSante et al. 1997).

1. Loose dogs and cats can directly affect Burrowing Owl habitat by digging
out the nest or removing chicks. OPTION: Leash law for dogs and requiring all cats to be house bound or
leashed in areas where burrowing owls are present. Implementation of a removal
program for all feral dogs and cats on public lands.

3. Burrowing Owls will nest near trails and along canal banks created for agriculture.
In these locations, burrows are susceptible to collapse from heavy farm equipment.OPTION: Where possible provide stable artificial burrows.

7. The poisoning of ground squirrels and destructive weed control practices
have caused a decline in migratory bird populations. OPTION: Carefully evaluate poison control methods and eliminate spraying
during breeding bird season.

MONITORING METHODS AND RESEARCH NEEDS:

Coordinated, range-wide research on population demographics needs to be conducted
to determine population declines (Holroyd and Wellicome 1997, Holroyd et al.
2001). The following are some suggested research needs:

1. Work to clarify status.

2. Conduct a standardized statewide survey to monitor population trends.

Collins, C.T. 1979. The ecology and conservation of burrowing owls. Pages 6-17
Proceedings of the National Audubon Society symposium of owls of the west, their
ecology and conservation, Scheaffer, P.P. and S.M. Ehlers (editors). National
Audubon Society Western Education Center, Tiburon, CA.

Desmond, M.J. and J.A. Savidge. 1998. Burrowing Owl conservation in the Great
Plains. Page 9 in Abstracts of the Second International Burrowing Owl Symposium,
Ogden, Utah.

DeSante, D.F., E.D. Ruhlen, S.L. Adamany, K.M. Burton, and S. Amin. 1997. A
census of burrowing owls in central California in 1991. Pages 38-48 in Lincer,
J.L. and K. Steenhof (editors). The Burrowing Owl; its biology and management:
including the Proceedings of the First International Burrowing Owl Symposium.
Raptor Research Report Number 9.

Holroyd, G.L., R. Rodriguez-Estrella, and S.R. Sheffield. 2001. Conservation
of the Burrowing Owl in western North America: issues, challenges and recommendations.
Journal of Raptor Research 35:399-407.